1. Field of the Invention
The present invention is generally related to an outboard motor and, more particularly, to an outboard motor that provides cooling of exhaust gas used in an exhaust gas recirculation EGR system.
2. Description of the Related Art
Those skilled in the art of internal combustion engines are familiar with the concept of exhaust gas recirculation. Various techniques, procedures, and equipment are known to those skilled in the art for the purpose of accomplishing exhaust gas recirculation.
U.S. Pat. No. 5,762,051, which issued to Okamoto on Jun. 9, 1998, describes an exhaust gas recirculation system for an engine. A method and device for controlling the nitrogen oxide production of an internal combustion engine having at least one cylinder with a cylinder head and an air intake and exhaust passage is described. The device comprises an exhaust gas recirculation system. In one embodiment, a portion of the exhaust gas produced by the engine is routed through a bypass line from the exhaust passage through a valve to the air intake passage. In another embodiment, the bypass line extends in the space between the two banks of a V-type engine along an intake manifold. In another embodiment, the bypass line is a passage extending through the cylinder head from an exhaust passage to a valve having an outlet in communication with the air intake passage leading to that cylinder.
U.S. Pat. No. 6,662,789, which issued to Hatano on Dec. 16, 2003, describes a water cooled exhaust gas recirculating device. It has a hole-open/closed mechanism allowing communication with outside air. The mechanism is arranged at a cooling water recirculation passage cooling an exhaust gas recirculation valve. A drain bolt is used as the hole-open/closed mechanism. The mechanism is arranged at a stopper stopping up a hole formed during manufacturing of the cooling water recirculation passage.
U.S. Pat. No. 7,089,890, which issued to Obidi on Aug. 15, 2006, describes a cooling system for an internal combustion engine with exhaust gas recirculation (EGR). A cooling system pumps coolant through parallel connections to a crankcase and an EGR cooler in an internal combustion engine with exhaust gas recirculation. A crankcase supply conduit connects a coolant pump to a coolant channel formed by the crankcase. The coolant channel is connected to a coolant chamber formed by the cylinder head. An EGR cooler supply conduit connects the EGR cooler to the coolant pump. The EGR cooler is connected to the coolant chamber. Coolant flows from the coolant pump into the crankcase supply conduit and into the EGR cooler supply conduit at essentially the same time and at essentially the same temperature. The coolant circulates from the coolant pump through the coolant channel into the coolant chamber. The coolant circulates from the coolant pump through the EGR cooler into the coolant chamber. The coolant returns to the coolant pump from the coolant chamber in the cylinder head.
U.S. Pat. No. 7,182,074, which issued to Redon et al. on Feb. 27, 2007, describes a manifold assembly for an internal combustion engine. The assembly includes a manifold body and first and second housings. The manifold body includes an EGR cooler cavity, an oil cooler cavity, and an air intake manifold. The first housing is adapted to provide a fluid to the EGR and oil cooler cavities. The second housing is adapted to receive the fluid from the EGR and the oil cooler cavities.
U.S. Pat. No. 7,185,642, which issued to Redon et al. on Mar. 6, 2007, describes a manifold body for an internal combustion engine. The body includes an EGR cooler cavity adapted to receive an EGR cooler, an oil cooler cavity adapted to receive an oil cooler, and an air intake manifold configured to provide a gas mixture to the internal combustion engine.
U.S. Pat. No. 7,275,526, which issued to Sugimoto et al. on Oct. 2, 2007, describes a multi-cylinder engine. The engine is capable of inhibiting an EGR cooler from being damaged and at the same time making the EGR cooler compact. On the assumption that a direction where a crankshaft spans in front as a front and rear direction and a widthwise direction of a cylinder head perpendicular to this front and rear direction is deemed as a lateral direction, an intake air distributing passage wall is attached to one lateral side surface of the cylinder head and an exhaust gas converging passage wall attached to the other lateral side of the cylinder head, the exhaust gas converging passage wall having an interior area communicated with an interior area of the intake air distributing passage wall through the EGR cooler. In this multi-cylinder engine, an intake air inlet pipe is made to stand up at an upper portion of the intake air distributing passage wall and the EGR cooler is above the intake air distributing passage wall. Further, the intake air inlet pipe is arranged side by side with the EGR cooler.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.